Understanding the failure mechanisms of embankment dams due to overtopping is essential for the design of flood mitigation, flood mapping, and flood warning systems. The breach process in embankment dams can be characterized using breach parameters such as breach opening dimensions, time of breach formation, and peak breach outflow. The main objective of this study is to derive new set of statistical equations to predict the target breach parameters. A database of 126 events of embankment failure was collected and then multiple nonlinear regression analysis is used to derive the new set of equations and the uncertainty in the computed parameters was quantified. Finally, five large-scale overtopping failure tests were conducted on cohesive and non-cohesive soils embankments. The derived breach parameters equations showed good agreement with the results of the physical models for non-cohesive soil embankments, while the failure of cohesive soil embankments varied significantly with soil properties; indicating that breach parameters in cohesive soil embankment should be computed based on not only embankment dimensions but soil properties as well.

It is a challenge to drill in highly deviated or horizontal holes with high differential pressures. Wellbore instability, differential sticking and mud loss are frequently encountered problems while drilling slanted wells in Kuwait across shale and sand series. Drilling became more challenging with considerable non-productive time. Therefore, it is necessary to identify a fluids solution when other options with casing zone isolation are not viable. Traditionally, oil-based mud (OBM) was used while drilling these formations with limited success. A customized fluid system was designed to overcome the issue of high overburden pressure in shale and sand series formations targeting effective bridging, minimizing pore pressure transmission, and strengthening the wellbore. A nano-size deformable synthetic polymer, along with sized calcium carbonate and graphite, was identified to effectively plug the pore throats and minimize fluid invasion, which was confirmed by particle plugging tests. A well section was identified to comingle the highly depleted and pressurized formations. This was the first attempt on a high-angle well with development drilling operations in Kuwait and was performed to facilitate the successful drilling of the reservoir. Traditional OBM was converted to a customized fluid system using a nano-size polymer and sized bridging additives based on proprietary software selection and a series of laboratory tests. Drilling and logging were successfully performed for the first time in the commingled section without incident. There was no wellbore instability or differential sticking tendencies, less torque and drag, as well as enhanced wellbore cleaning in the high-angle sections. This paper also presents some successful applications of the nano-size deformable polymer in OBM to drill highly depleted formations in HTHP wells managing up to 3500 psi overbalance across highly permeable formations.

No abstract

Formatted: Centered Formatted: Font: 8 pt, Complex Script Font: 8 pt environmental and economical settings on the study area. Furthermore, by changing the linguistic quantifiers, the GIS-based AHP-OWA can generate a wide range of decision strategies.

No abstract